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4 Safety Function Blocks
NX-series Safety Control Unit Instructions Reference Manual (Z931)
4
SF_MutingPar_2Sensor
• Muting is used to intentionally disable a safety function. Muting is used, for example, to pass a work-
piece through a hazardous area without stopping the machine. Muting is activated by muting sen-
sors. Two muting sensors are used. To correctly incorporate the safety function into a manufacturing
process, you must ensure that people will not enter the hazardous area while the light curtain is being
muted. Pushbuttons, proximity sensors, photoelectric barriers, limit switches, and other devices that
do not have failsafe mechanisms are used for muting sensors. Muting operation must be indicated by
indicator lights.
• There are two types of muting: parallel and sequential. This FB performs parallel muting with two
muting sensors. An application example is provided below. (Refer to SF_MutingPar_2Sensor Instruc-
tion Application Example with Two Reflective Light Barriers on page 4-84.) The sensors must be
located as described in Annex F.7 in CD 2005 of IEC 62046, as shown in the application example.
The FB can be used for either forward or backward passage. However, the actual direction cannot be
identified. To prevent manual operation, muting must also be enabled by process control with the
MutingEnable signal to perform muting.
• The input parameters to the FB include two muting sensor signals (S_MutingSwitch11 and
S_MutingSwitch12), an OSSD signal from a photoelectric protection device (S_AOPD_In), and two
time parameters (DiscTimeEntry and MaxMutingTime).
• Activate the S_StartReset input only when you can ensure that no hazardous state will occur as the
result of starting the Safety CPU Unit.
MutingEnable BOOL TRUE or FALSE FALSE A constant or a variable. It is a command from the control
system to enable starting muting as required in the
machine cycle. You can change this signal to OFF after
muting starts.
FALSE: Disables muting.
TRUE: Enables starting muting.
S_StartReset SAFEBOOL TRUE or FALSE FALSE Refer to Safety FB Common Input Variables on page 4-2.
Reset BOOL TRUE or FALSE FALSE Refer to Safety FB Common Input Variables on page 4-2.
Output Variables
Variable Data type Valid range Default Description
Ready BOOL TRUE or FALSE FALSE Refer to Safety FB Common Output Variables on page 4-4
S_AOPD_Out SAFEBOOL TRUE or FALSE FALSE This safety output gives the status of the protection
devices that is being muted.
FALSE: Something has entered the AOPD protected area
and muting is disabled.
TRUE: Nothing has entered the AOPD protected area and
muting is enabled.
S_MutingActive SAFEBOOL TRUE or FALSE FALSE Gives the muting status.
FALSE: Muting is disabled.
TRUE: Muting is enabled.
Error BOOL TRUE or FALSE FALSE Refer to Safety FB Common Output Variables on page
4-4.
DiagCode WORD Depends on state
code.
16#0000 Refer to Safety FB Common Output Variables on page
4-4.
Function
Variable Data type Valid range Default Description
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